Many computer systems utilize a backplane, a circuit board into which other circuit boards or circuit cards connect. A single backplane can include various connectors to accommodate multiple different circuit cards. Some circuit cards are easily removable and plug-in to a connector on a surface of the backplane, and other circuit cards are more permanently mounted to the backplane.
Some computer systems utilize a card cage that encloses the backplane. Many card cages conform to predefined industry standards, such as the Compact Peripheral Component Interconnect (CPCI) standard or the Versa Modular Eurocard (VME) standard. These standards ensure that card cages have the same or similar designs. A CPCI card cage, for example, has four metal extrusions that are fixed or mounted to one side of the backplane.
Backplanes have limited area to accept circuit cards and other electronic components. In some instances, the size of a backplane must conform to standard form factors (i.e., manufacture established width to length ratios). Thus, designers endeavor to efficiently utilize space on the surfaces of the backplane to accommodate a large number of circuit cards and electronic components. Designs that utilize space more effectively decrease the size of the computer system and decrease manufacturing costs.
As another feature, circuit cards and other electronic components connected to the backplane are preferably easily accessible and readily removable. Construction and repair of a computer system is more complex and costly if components are difficult to service. For example, a single backplane can contain multiple circuit cards that are each individually secured to the backplane with screws or fasteners. If a tool is required to remove each circuit card, then servicing the backplane is labor intensive.